The Applicant has developed a page width ink jet print head that is the subject of a large number of United States patents and patent applications. The print head is capable of printing text and images having resolutions as high as 1600 dpi.
An integral part of the print head is one or more print head chips. The print head chips are the product of an integrated circuit fabrication technique. In particular, each print head chip comprises a plurality of nozzle arrangements that are positioned along a length of silicon wafer substrate. Each nozzle arrangement is in the form of a micro electro-mechanical system. The applicant has developed technology that allows for the fabrication of such print heads having up to 84 000 nozzle arrangements.
In general, during assembly of a print head, the print head chips are positioned in some form of carrier. The carrier forms part of an ink distribution arrangement such as an ink distribution manifold. Instead, the carrier can itself be attached in some way to an ink distribution arrangement to define some form of interface between the print head chips and the ink distribution arrangement.
The positioning of the print head chips in their respective carriers usually takes place by way of simply urging the print head chip into a recess defined in the carrier. The recess is thus dimensioned so that the fit is a snug fit or an interference fit to ensure that the print head chip is retained in position in the carrier.
Due to the elongate nature of the print head chip, the print head chip is susceptible to flexure. As a result, any stresses that are exerted on the carrier during normal handling and operation can result in flexure of the carrier and thus the print head chip. It will be appreciated by those of ordinary skill in the art that the fact that the nozzle arrangements are each in the form of a micro electro-mechanical system makes such flexure highly undesirable.
A particular problem with such a fit stems from the possible ingress of particulate matter into the recess. This is especially so if the matter is in the form of one or more relatively hard particles. When the chip is urged into the recess, such a particle can become sandwiched between the print head chip and a wall of the recess. This results in a region of stress concentration at that point on the print head chip that is impinged upon by the particle. Thus, when the chip is subjected to a small amount of flexure that would usually not cause a problem, the stress concentration can cause a fracturing of the print head chip.
The Applicant has conceived the present invention to address this problem and to alleviate the necessity for the print head manufacturer to achieve a particulate free environment for the assembly stage of the print head. As is well known, chip manufacturers incur substantial expense to ensure that chip fabrication environments are kept sterile. Applicant believes that it is desirable that the need for such sterile environments does not extend to the print head assembly stage.